$(document).ready(function() {
        $("#btn").click(function () {
              var url = location.href.replace(/(&)(.+)/g, ""),
              t1 = $("#s1 select option:selected").val(),
              t2 = $("#s2 select option:selected").val();
              console.log(location.href);
              if(t1.length == 0 || t2.length == 0){
                  alert("Please select both teams.");
                  return false;
              }
              if(t1 === t2){
                  alert("Please select two different teams.");
                  return false;
              }
              window.location = url + '&t1=' + t1 + '&t2=' + t2;
              return false;
       });       
});